Air-blast circuit breaker with double nozzle



Sept 14, 1965 J. A. K. JusslLA 3,206,582

AIR-BLAST CIRCUIT BREAKER WITH DOUBLE NOZZLE Filed Dec. 5, 1962 Rm ,ma

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United States Patent O 3,206,582 AIR-BLAST CIRCUIT BREAKER WITH DOUBLE NOZZLE Jukka A. K. Jussila, Gebenstof, Switzerland, assignor toAktiengesellschaft Brown, Boveri & Cie., Baden, Switzerland, ajoint-stock company Filed Dec. 5, 1962, Ser. No. 242,481

Claims priority, application Switzerland, Dec. 7, 1961,

14,207/ 61 3 Claims. (Cl. 200--148) The invention concerns lan air-blastcircuit breaker with a double nozzle, one of the nozzles acting as thefixed contact element and the other one as the movable contact element.When these circuit breakers are in the open position, the separatedcontacts are kept under air pressure.

In order to be able to operate such a circuit breaker it is necessary toprovide complicated control equipment. It is necessary not only toactuate the contacts but also additional valves which ensure that thecontacts are subjected to a blast of compressed `air and that thepressure air remains in the arc extinguishing chamber after interruptionhas occurred. This necessitates the provision of several control pipeswhich are supplied with air from the compressed air container where thepressure differs from that in the arc extinguishing chamber.

It is therefore desirable that the control system for such circuitbreakers should be simplified. This is achieved in accordance with theinvention by arranging an exhaust valve at the rear end of each nozzle,one of these valves being at the same time an operating valve while theother valve is connected to a piston which shuts oit a container whichis constantly under pressure.

A constructional example of a circuit breaker according to the inventionis illustrated schematically in the accompanying drawing. The circuitbreaker is shown in the figure in the position required for theoccurrence of the air blast.

Located inside the switch chamber 1 are the two coaxial tubular contacts2, 3. In the present example contact 2 is stationary and contact 3 ismovable. The movable contact 3 is provided with a piston 4 against whicha spring 18 exerts a pressure. Piston 4 operates within a cylinder part6a of a housing and the other part 6b of this housing serves toaccommodate spring 18 and functions as a chamber for exhaust valve 6.Reference number 5 indicates the exhaust valve easing of the fixedcontact 2 and 6 is the exhaust valve for the movable contact 3. Valve 5comprises a valve disc 7 land a piston 8 which is joined to the valvedisc by means of a spindle 9. Piston 8 is provided with holes 11 whichcan be closed by a non-return plate 10. Behind the piston there is achamber 13 in which a certain pressure is maintained. Furthermore, thereis an lopening 12 through which air can slowly escape from chamber 13.The control system is indicated by the control element 19 which can beactuated lby way of the control pipe 20. The line 23 indicates aconnection to an interlocking `device 21. The locking device 21 forpiston 4 serves to maintain it and hence contact member 3 disengagedfrom contact member 2 for as long as it is desired to maintain thecontacts in their disengaged position. Contact member 3 can be releasedso as to shift to the left by the restoring force built up incompression spring 19 by releasing the locking device from piston 4 witha pressure pulse transmitted over line 23 from the control element 19.This locking device per se is conventional and can be found moreparticularly described and illustrated in German Patent No. 1,049,954,dated February 5, 1959. Compressed air is supplied by Way of pipe 22 tothe switch or extinguishing chamber 1. By numeral 24 is designated aninsulating 3,206,582 Patented Sept. 14, 1965 ICC support for thestationary hollow contact 2, the support being clamped between switchchamber 1 and valve housing 5.

In the closed position of the hollow contact members 2, 3 as indicatedby the broken line position of contact member 3, valves 6 and 7 will bein their closed positions as indicated by the broken lines. Moreover,the interior of these contact members as well as the housing for valve 6and housing 5 of valve 7 and the interior of chamber 13 will have beenre-iilled with pressure gas from switch chamber 1 flowing into thelatter while contacts 2 and 3 were held in a separated condition bylocking device 21.

The method of operation for disconnections is as follows:

Exhaus-t valve 6 is opened vby means of control element 19 due tocompressed air from control pipe 20 acting yon the element, whereuponcompressed air flows from the inside of tubular contacts 2 and 3 to theoutside. Piston 4 is, however, still subjected to the full pressure ofthe compressed air, so that tubular contact 3 is moved against thespring 18 and the contacts separate. Compressed air then flows from theextinguishing chamber into the tubular contacts 2, 3 as indicated by thearrows in the figure. As a result, the arc which has occurred isextinguished. Piston 4 passes beyond the interlocking device 21 whichholds the movable contact 3 in a fixed position. On the other hand,there is also a drop in pressure in chamber 15, so that the compressedair in cham ber 13 acts on piston 8. Valve 7 is opened and compressedair can now flow through opening 16. Nonreturn valve 10 closes theopenings 11 in piston 8, so that the pressure is rst of all maintainedin chamber 13. Air escapes slowly through the opening 12 so that thepressure in chamber 13 decreases somewhat after a certain time. In themeantime valve 6 closes again due to the blast pressure which acts onthe valve. Similarly, due to spring 17 and the blast pressure, valvedisc 7 is moved towards the left against the somewhat reduced pressurein chamber 13 and closes the exhaust port 16 so that the extinguishingchamber 1 is closed again and can be refilled with compressed airsupplied by way of compressed lair pipe 22. This compressed air ensuresthat the electric strength between contacts 2 and 3 is adequate.

Chamber 13 is refilled with air again which flows through the openings11 which only open when the pressure in the extinguishing chamber ishigher than that in chamber 13.

If the circuit breaker has to be closed, interlocking device 21 isreleased, whereupon spring 18 causes piston 4 and movable contact 3 tomove towards fixed contact 2 until the contacts are closed. Exhaustvalves 6 and 7 remain closed during this operation.

With this arrangement, exhaust valve 7 is actuated by the compressed airwhich passes through the hollow con- -tacts 2 4and 3 when in the closedposition. A special air supply pipe for actuating the exhaust valve 7can be dispensed with.

The advantage of this arrangement is the saving in control piping forcircuit breakers with double nozzles which are kept under pressure whenin the open condition.

What I claim is:

1. In an air-blast circuit breaker the combination comprising a casingestablishing therein a switch chamber which is continuously subjected toa lling with compressed air, a pair of tubular contact members arrangedco-axially within said switch chamber, said tubular contact membersincluding nozzle type inlets at one end thereof adapted to engage eachother, one of said contact members being stationary and the othermovable and including a spring loaded piston member always having oneside thereof exposed to the pressure of the air within said switchchamber, a first housing located within said switch chamber and whichincludes a cylinder for said piston in one part thereof and a valvechamber in .another part thereof in communication with the other end ofsaid movable contact member and also with the other side of said pistonmember, a first spring loaded exhaust valve in said valve chamber, saidexhaust valve being closed to close oitsaid valve chamber when thenozzle ends of said contact members are engaged and actuata'bie to anopen position to vent said valve chamber and the interior of saidmovable contact member to atmosphere when it is desired to effectdisengagement of said contact members, a second housing communicatingwith the opposite end of said stationary contact member, a normallyclosed second exhaust valve located in one part of said second housingand which controls the venting of said stationary contact member toatmosphere, and a second piston connected to said second exhaust valve,said second piston being slidable in a cylinder part of said secondhousing and always exposed on one side to the air pressure withinsaid'second housing, the other side of said second piston together withsaid cylinder establishing a pressure chamber effective to shift saidsecond piston and said second exhaust Valve to the open position upon adrop in air pressure in the part of said second housing which containssaid second exhaust valve.

2. An air blast circuit breaker as delined in claim 1 wherein saidsecond piston is provided with openings therethrough controlled bynon-return valve means for passing compressed air into said pressurechamber when said second exhaust valve is closed.

3. An air blast circuit breaker as defined in claim 1 wherein saidsecond piston is provided with openings therethrough controlled bynon-return valve means for passing compressed air into said pressurechamber when said -second exhaust valve is closed, and which alsoincludes spring means biasing said second exhaust valve to a closedposition, said second piston also including a bleed opening therethroughfor equalizing the pressure in said pressure chamber and that part ofVsaid second housing which contains said second exhaust valve after saidnon-return valves have closed.

References Cited by theExaminer UNITED STATES PATENTS 2,574,334 l1/51Latour ZOO- 148 3,093,717 6/63 Forwald ZOO-148 BERNARD A. GILHEANY,Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

1. IN AN AIR-BLAST CIRCUIT BREAKER THE COMBINATION COMPRISING A CASINGESTABLISHING THEREIN A SWITCH CHAMBER WHICH IS CONTINUOUSLY SUBJECTED TOA FILLNG WITH COMPRESSED AIR, A PAIR OF TUBULAR CONTACT MEMBERS ARRANGEDCO-AXIALLY WITHIN SAID SWITCH CHAMBER, SAID TUBULAR CONTACT MEMBERSINCLUDING NOZZLE TYPE INLES AT ONE END THEREOF ADAPTED TO ENGAGE EACHOTHER, ONE OF SAID CONTACT MEMBERS BEING STATIONARY AND THE OTHERMOVABLE AND INCLUDING A SPRING LOADED PISTON MEMBER ALWAYS HAVING ONESIDE THEREOF EXPOSED TO THE PRESSURE OF THE AIR WITHIN SAID SWITCHCHAMBER, A FIRST HOUSING LOCATED WITHIN SAID SWITCH CHAMBER AND WHICHINCLUDES A CYLINDER FOR SAID PISTON IN ONE PART THEREOF AND A VALVECHAMBER IN ANOTHER PART THEREOF IN COMMUNICATION WITH THE OTHER END OFSAID MOVABLE CONTACT MEMBER AND ALSO WITH THE OTHER SIDE OF SAID PISTONMEMBER, A FIRST SPRING LOADED EXHAUST VALVE IN SAID VALVE CHAMBER, SAIDEXHAUST VALVE BEING CLOSED TO CLOSE OFF SAID VALVE CHAMBER WHEN THENOZZLE ENDS OF SAID CONTACT MEMBERS ARE ENGAGED AND ACTUATABLE TO ANOPEN POSITION TO VENT SAID VALVE CHAMBER AND THE INTERIOR OF SAIDMOVABLE CONTACT MEMBER TO ATMOSPHERE WHEN IT IS DESIRED TO EFFECCTDISENGAGEMENT OF SAID CONTACT MEMBERS, A SECOND HOUSING COMMUNICATINGWITH THE OPPOSITE END OF SAID STATIONRAY CONTACT MEMBER, A NORMALLYCLOSED SECOND EXHAUST VALVE LOCATED IN ONE PORT OF SAID SECOND HOUSINGAND WHICH CONTROLS THE VENTING OF SAID STATIONARY CONTACT MEMBER TOATMOSPHERE, AND A SECOND PISTON CONNECTED TO SAID SECOND EXHAUST VALVE,SAID SECOND PISTON BEING SLIDABLE IN A CYLINDER PART OF SAID SECONDHOUSING AND ALWAYS EXPOSED ON ONE SIDE TO THE AIR PRESSURE WITHIN SAIDSECOND HOUSING, THE OTHER SIDE OF SAID SECOND PISTON TOGETHER WITH SAIDCYLINDER ESTABLISHING A PRESSURE CHAMBER EFFECTIVE TO SHIFT SAID SECONDPISTON AND SAID SECOND EXHAUST VALVE TO THE OPEN POSITION UPON A DROP INAIR PRESSURE IN THE PART OF SAID SECOND HOUSING WHICH CONTAINS SAIDSECOND EXHAUST VALVE.